1. Field of the Invention
The present invention relates to a wiring route structure for an actuator arm assembly that is used in a disk storage such as a magnetic disk storage (also called a hard-disk drive). More specifically, the invention relates to an actuator arm assembly and a disk storage equipped with a wiring route structure for fixing a lead wire between the coil of a voice coil motor and a flexible cable.
2. Description of Related Art
FIG. 1 is a plan view of a conventional magnetic disk storage (hard-disk drive) 10. A plurality of magnetic disks 11 are stacked at regular intervals, and each magnetic disk 11 is fitted on a spindle 19 through the center hole of the disk and is spun at a constant speed. The magnetic disk 11 uses both sides thereof as storage areas. An actuator arm assembly 21 (hereinafter referred to as a "comb type actuator arm assembly") includes a comb type carriage 14 and head/suspension assemblies 13. To the point end 12 of the head/suspension assembly 13, a slider (not shown) with a magnetic head is attached so as to face the corresponding magnetic disk 11, while the rear end swage portion 30 is joined to the arm portion of the comb type carriage 14 by swaging. A portion of the comb type carriage 14 is formed as a coil support portion 22, and a coil 26 is fixed to the inner side of the coil support portion 22 with an adhesive agent. A voice coil motor portion 15 has permanent magnets interiorly and the coil 26 is held in the magnetic field present between the magnets. The lead wires extending from the coil 26 and the lead wires extending from the magnetic heads respectively are connected to a control unit 17 through a flexible cable 16 and a circuit board 20. The control unit 17 causes a controlled current to flow through the coil 26, thereby rotating the actuator arm assembly 21 on a pivot shaft 18. The rotation of the actuator arm assembly 21 positions the magnetic head over a desired track on the magnetic disk 11.
FIG. 2 is a perspective view of the comb type actuator arm assembly 21, and FIG. 3 is a side view of the comb type carriage 14 constituting a portion of the actuator arm assembly 21. Two lead wires 27 and 28 extend from the start end and terminal end of the coil 26 and are connected to the flexible cable 16. A portion of the coil support portion 22 is provided with a lead wire holder 23, which is formed to provide a groove at a wiring route of the lead wires 27 and 28 for inserting and fixing the lead wires covered with insulating tubes. The lead wires 27 and 28 are inserted into the groove formed by the lead wire holder 23 and are fixed to the coil support portion 22 with an adhesive agent. The primary reason why the lead wires 27 and 28 are fixed to the coil support portion is to prevent force from being applied to the lead wires 27 and 28 during the fabrication process, and thereby causing the wire of the coil 26 to separate from the coil 26 or coil support portion 22. Another reason is to allow for accurately wiring the lead wires 27 and 28 in a limited space along predetermined wiring route. Still another reason the lead wires 27 and 28 are fixed is for preventing the lead wires 27 and 28 from giving rise to an insulation defect by moving during operation of the actuator arm assembly 21 and touching the inner constituent components of the magnetic disk storage, or from having influence on the motion characteristic of the actuator arm assembly 21. The point ends of the lead wires 27 and 28 fixed with the lead wire holder 23 are electrically connected on a cable connecting board 24 to the flexible cable 16. The flexible cable connecting board 24 is fixed to the comb type carriage 14 by a screw 25.
The comb type carriage 14 shown in FIG. 3 is integrally molded by aluminum die casting. In the molding of the comb type carriage 14 by aluminum die casting, the configuration of the lead wire holder 23 can be easily selected, so it is not limited to the configuration shown in FIG. 2 but may be formed into other configurations such as a groove. Therefore, in the comb type actuator arm assembly, the lead wire fixing means between the coil 26 and the flexible cable 16 is obtainable comparatively easily.
However, a further reduction in the width of the magnetic disk storage has been pursued in recent years, so there has arisen a need to narrow the spacing between stacked magnetic disks even further. In the aforementioned comb type actuator arm assembly 21, the swaged portion 30 joining the head/suspension assemblies 13 and the comb type carriage 14 together becomes one obstacle in shortening the spacing between magnetic disks stacked, because the swaged portion occupies space in an up-and-down direction. On the other hand, an actuator arm assemblies using no comb type carriage (hereinafter referred to as a "stacked type actuator arm assembly") is becoming adopted. In the stacked type actuator arm assembly, each head/suspension assembly is integrally formed from the head-attached portion 12 to the pivot-shaft inserting portion, and these head/suspension assemblies are stacked on the pivot shaft 18 with spacers between them, so the stacked type actuator requires no swaged portion provided in the comb type actuator arm assembly and is suitable for thinning the magnetic disk storage.
In the stacked type actuator arm assembly, at least one of a plurality of spacers is equipped with a coil support portion. However, since the spacer is formed by pressing, it is not easy to form a lead wire holder, such as the one formed in the comb type carriage formed by aluminum die casting, in the coil support portion of the spacer. In addition, in a miniaturized magnetic disk storage there is not enough space around the periphery along the route for wiring the lead wires, so there is a need to wire the lead wires accurately along a predetermined route and keep them held on the predetermined route even during operation.
Accordingly, it can be seen there is a need to provide a stacked type actuator assembly equipped with a structure for easily fixing lead wires between a coil and a flexible cable.